Sample injection with fluidic connection between fluid drive unit and sample accommodation volume

ABSTRACT

An injector, for injecting a fluidic sample into a flow path between a fluid drive and a sample separation unit, includes a sample accommodation volume, a sample drive, and a fluidic valve switchable to selectively couple the volume with the flow path or decouple the volume from the flow path. In an injection switching state, the fluid drive, the separation unit and the sample drive are coupled by the valve so that fluid driven by the sample drive and flowing from the volume to the separation unit and further fluid driven by the fluid drive and flowing from the fluid drive to the separation unit are combined at a fluidic connection upstream of the separation unit. A control unit controls a pressure of the fluid and/or the further fluid during injecting.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(a) to GermanPatent Application No. DE 10 2016 109 906.6, filed May 30, 2016, thecontent of which is incorporated herein by reference in its entirety.

BACKGROUND ART

The present invention relates to injectors, a sample separationapparatus, and methods of injecting a fluidic sample.

In liquid chromatography, a fluidic sample and an eluent (liquid mobilephase) may be pumped through conduits and a separation unit such as acolumn in which separation of sample components takes place. The columnmay comprise a material which is capable of separating differentcomponents of the fluidic sample. The separation unit may be connectedto other fluidic members (like a sampler or an injector, a detector) byconduits. Before the fluidic sample is introduced into a separation pathbetween a fluid drive unit (in particular a high pressure pump) and theseparation unit, a predefined amount of fluidic sample shall be intakenfrom a sample source (such as a sample container) via an injectionneedle into a sample loop by a corresponding movement of a piston withina metering device. This usually occurs in the presence of asignificantly smaller pressure than what the separation unit is runwith. Thereafter, an injector valve is switched so as to introduce theintaken amount of fluidic sample from the sample loop of a metering pathinto the separation path between fluid drive unit and the separationunit for subsequent separation.

Injector valves may be configured as rotatable valves having a stator(which may have one or a plurality of fluid ports) and a rotor (whichmay have a plurality of grooves for connecting respective ones of thefluid ports) being rotatable with regard to the stator to therebyestablish a desired fluid communication state between fluid ports andgrooves. In order to be capable to withstand high pressure values of forinstance up to 1200 bar in a fluid tight manner, it is necessary topress the rotor against the stator.

U.S. Pat. No. 3,940,994 discloses a high pressure sample injector forliquid chromatographs. The apparatus includes a structure defining acylindrical dispensing chamber for receiving the sample to be injectedinto the flow path of a high pressure stream of carrier fluid in aliquid chromatograph. Control structure is interposed between thedispensing chamber and the flow path of the carrier stream forpreventing liquid flow from the carrier stream to the dispensingchamber, and for enabling flow in the opposite direction only when thepressure in the dispensing chamber at least equals the carrier streampressure. A pressurizing apparatus is connected to the dispensingchamber to raise its pressure, when desired, to a value at least equalto that of the carrier stream, in order that the sample may be injectedinto the carrier without reducing the carrier stream pressure.

US 2015/0226710 discloses a method for feeding a sample into an analysisbranch of a liquid chromatography system. A solvent or a solvent mixturefrom at least one solvent branch is supplied as first volume flow intothe analysis branch. At least one sample from at least one sample branchis fed as second volume flow into the analysis branch within apredetermined time interval. The volume flow is reduced to an extentduring the predetermined time interval, and a third volume flowresulting from the sum of the volume flows remains substantiallyconstant in the analysis branch.

US 2016/0069844 discloses a method and a system for injecting a sampleinto a flow of a liquid chromatography system. The method includescombining a flow of a sample and a flow of a mobile phase to create adiluted sample in the system flow. The volumetric flow rate of thesample is controlled to be at a value that yields a desired dilutionratio for the diluted sample. The particular value at which thevolumetric flow rate is maintained can be determined from the desiredvalue of the dilution ratio and the volumetric flow rate of the mobilephase. System embodiments include a syringe that can be used to providea sample solution at a controllable volumetric flow rate for combinationwith a high pressure mobile phase.

However, the functionality of conventional injectors is limited.

SUMMARY

It is an object of the invention to provide a flexibly operableinjector.

According to an exemplary embodiment of the present invention, aninjector (which may also be denoted as sampler) for injecting a fluidicsample (wherein a fluid may be a liquid and/or a gas, optionallycomprising solid particles) into a flow path between a fluid drive(which may also be denoted as a mobile phase drive and which may beconfigured as a high pressure pump) and a separation unit (such as achromatographic separation column) of a sample separation apparatus (forinstance a liquid chromatography apparatus) is provided, wherein theinjector comprises a sample accommodation volume (such as a sample loop)for accommodating the fluidic sample prior to injecting, a sample drive(such as a metering pump, for instance a syringe pump) configured forintaking the fluidic sample into the sample accommodation volume, afluidic valve (in particular a rotor valve comprising a stator, havingat least fluidic ports and optionally fluidic conduits, and a rotor,having fluidic conduits, being rotatable relative to one another)switchable between multiple switching states to thereby selectivelycouple (i.e. fluidically couple) the sample accommodation volume withthe flow path or decouple (i.e. fluidically decouple) the sampleaccommodation volume from the flow path, wherein in an injectionswitching state of the fluidic valve, a fluidic coupling may beestablished between the fluid drive, the separation unit and the sampledrive by the fluidic valve so that fluid (such as the fluidic sample)driven by the sample drive and flowing from the sample accommodationvolume to the separation unit and further fluid (such as a mobile phase)driven by the fluid drive and flowing from the fluid drive to theseparation unit are combined at a fluidic connection (such as a fluidicT-piece or any other fluidic bifurcation or network) upstream of theseparation unit, and a control unit (such as a processor, for instance amicroprocessor or a CPU, central processing unit) configured forcontrolling (in particular adjusting) a pressure of at least one of thegroup consisting of the fluid driven by the sample drive, the furtherfluid driven by the fluid drive, and the combined fluid (i.e. themixture of the fluid driven by the sample drive and the further fluiddriven by the fluid drive) during injecting fluidic sample from thesample accommodation volume into the flow path.

According to another exemplary embodiment, an injector for injecting afluidic sample into a flow path between a fluid drive and a separationunit of a sample separation apparatus is provided, wherein the injectorcomprises a sample accommodation volume for accommodating the fluidicsample prior to injecting, a sample drive configured for intaking thefluidic sample into the sample accommodation volume, and a fluidic valveswitchable between multiple switching states to thereby selectivelycouple the sample accommodation volume with the flow path or decouplethe sample accommodation volume from the flow path, wherein in aninjection switching state of the fluidic valve, the fluid drive, theseparation unit and the sample drive are fluidically coupled at afluidic coupling point which is defined by a fluid port of the fluidicvalve (for instance a valve-internal flow coupler) so that fluid drivenby the sample drive and flowing from the sample accommodation volume tothe separation unit and further fluid driven by the fluid drive andflowing from the fluid drive to the separation unit are combined at thefluidic coupling point upstream of the separation unit (wherein thecombined fluid may flow together towards the separation unit).

According to still another exemplary embodiment, an injector forinjecting a fluidic sample into a flow path between a fluid drive and aseparation unit of a sample separation apparatus is provided, whereinthe injector comprises a sample accommodation volume for accommodatingthe fluidic sample prior to injecting, a sample drive configured forintaking the fluidic sample into the sample accommodation volume, and afluidic valve switchable between multiple switching states to therebyselectively couple the sample accommodation volume with the flow path ordecouple the sample accommodation volume from the flow path, wherein inan injection switching state of the fluidic valve, the fluid drive, theseparation unit and the sample drive are fluidically coupled by thefluidic valve so that fluid driven by the sample drive and flowing fromthe sample accommodation volume to the separation unit and further fluiddriven by the fluid drive and flowing from the fluid drive to theseparation unit are combined at a fluidic connection upstream of theseparation unit, wherein the fluidic valve is configured to beswitchable in another (in particular in an additional or an alternative,in terms of the analysis of a certain fluidic sample) injectionswitching state in which the fluidic sample is injected towards theseparation unit driven by the fluid drive while the sample accommodationvolume is located downstream of the fluid drive and upstream of theseparation unit (in particular, a flow of fluid may be established inthe described other injection switching state from the fluid drive,through the fluidic valve, the sample drive, the sample accommodationvolume, again the fluidic valve and towards the separation unit; afluidic connection configured as a fluidic T-piece or the like, asdescribed above, may be omitted in the other injection switching state).

According to still another exemplary embodiment, a method of injecting afluidic sample into a flow path between a fluid drive and a separationunit of a sample separation apparatus is provided, wherein the methodcomprises intaking fluidic sample in a sample accommodation volume of aninjector, switching a fluidic valve of the injector into an injectionswitching state in which the fluidic valve fluidically couples the fluiddrive, the sample drive and the separation unit so that fluid driven bythe sample drive and flowing from the sample accommodation volume to theseparation unit and further fluid driven by the fluid drive and flowingfrom the fluid drive to the separation unit are combined at a fluidicconnection upstream of the separation unit to thereby inject the fluidicsample from the sample accommodation volume in the flow path in theinjection switching state, and controlling a pressure of at least one ofthe group consisting of the fluid driven by the sample drive, thefurther fluid driven by the fluid drive, and the combined fluid (inparticular controlling the pressure at the fluidic connection betweenthe fluid drive, the sample drive and the separation unit) during theinjecting.

According to still another exemplary embodiment, a method of injecting afluidic sample into a flow path between a fluid drive and a separationunit of a sample separation apparatus is provided, wherein the methodcomprises intaking fluidic sample in a sample accommodation volume of aninjector, switching a fluidic valve of the injector into an injectionswitching state in which the fluidic valve fluidically couples the fluiddrive, the sample drive and the separation unit at a fluidic couplingpoint which is defined by a fluid port of (in particular a fluid portwithin) the fluidic valve so that fluid driven by the sample drive andflowing from the sample accommodation volume to the separation unit andfurther fluid driven by the fluid drive and flowing from the fluid driveto the separation unit are combined at the fluidic coupling pointupstream of the separation unit, whereby the fluidic sample is injectedfrom the sample accommodation volume into the flow path in the injectionswitching state.

According to still another exemplary embodiment, a method of injecting afluidic sample into a flow path between a fluid drive and a separationunit of a sample separation apparatus is provided, wherein the methodcomprises intaking fluidic sample in a sample accommodation volume of aninjector, switching a fluidic valve of the injector into an injectionswitching state in which the fluidic valve fluidically couples the fluiddrive, the sample drive and the separation unit, injecting the fluidicsample from the sample accommodation volume in the flow path in theinjection switching state so that fluid driven by the sample drive andflowing from the sample accommodation volume to the separation unit andfurther fluid driven by the fluid drive and flowing from the fluid driveto the separation unit are combined at a fluidic connection upstream ofthe separation unit, and (in particular previously, subsequently oralternatively) switching the fluidic valve in another injectionswitching state in which the fluidic sample is injected towards theseparation unit driven by the fluid drive while the sample accommodationvolume (and optionally also the sample drive) is located downstream ofthe fluid drive and upstream of the separation unit.

According to still another exemplary embodiment, a sample separationapparatus for separating a fluidic sample is provided, wherein thesample separation apparatus comprises a fluid drive configured fordriving a mobile phase, a separation unit configured for separating thefluidic sample in the mobile phase, and an injector having theabove-mentioned features for injecting the fluidic sample into a flowpath between the fluid drive and the separation unit.

According to a first aspect of an exemplary embodiment, an injectorarchitecture is provided in which the fluid drive, the separation unitand the sample drive are fluidically coupled by the fluidic valve in aninjection switching state for instance in a sort of a fluidicT-connection with a provision for controlling the pressure of one ormore of the at least three involved fluid streams, in particular at oraround this fluidic connection. The capability of pressure controlduring injection with a simultaneous fluidic coupling of separation unitwith both fluid drive (also denoted as mobile phase drive) and sampledrive (arranged as a part of an injector) allows for a reproducible andprecise sample injection procedure. By such an additional flow ratecontrol, it may be also possible to precisely control the fluidiccontributions of fluid flowing from the fluid drive to the separationunit and flowing from the sample drive to the separation unit and beingcombined at the flow combiner or fluidic connection. Pressure adjustmentallows for a particular simple, straightforward and error robust systemcontrol.

According to a second aspect of an exemplary embodiment, a fluidiccoupling point between a fluid drive, a separation unit, and a sampledrive may be defined functionally by or even spatially in an interior ofa fluidic valve, in particular in a stator of the fluidic valve. Inother words, the fluidic connection or flow combiner may be structurallyintegrated into the fluidic valve and may be constituted by a mutualcooperation between ports and fluid conduits of such a fluidic valve. Insuch a switchable fluidic valve, the mentioned fluidic T-connection orthe like may be established only in a particular switching state (inparticular in an injection switching state), whereas the fluidicT-connection or the like may be removed, deactivated or eliminated byswitching the fluidic valve into another switching state than theinjection switching state. Thus, the flexibility of a user to establishdifferent fluidic configurations by only a single fluidic valve issignificantly increased. By defining the fluidic connection orbifurcation point of the fluidic T-piece by a static fluidic port(rather than outside of the fluidic valve or in a fluidic conduitthereof) and hence as part of the stator of the fluidic valve, aprecisely defined and reproducible fluidic connection may be establishedwhile simultaneously obtaining a very small dead volume.

According to a third aspect of an exemplary embodiment, a fluidic valvein an injector is provided which is capable of flexibly switchingbetween at least two different injection modes (assigned to twodifferent injection switching states of the fluidic valve) of injectinga fluidic sample in a flow path towards a separation unit. In a firstinjection mode corresponding to an injection switching state of thefluidic valve, a fluidic T-connection or the like may be establishedbetween the fluid drive, the sample drive and the separation unit, sothat a definable (for instance by pressure adjustment) mixture betweenmobile phase pumped by the fluid drive and fluidic sample pumped by thesample drive may be transported towards the separation unit. However, ina second injection mode corresponding to a further injection switchingstate of the fluidic valve, a mobile phase may be pumped by the fluiddrive through the sample drive and the sample accommodation volume,thereby pumping the fluidic sample towards the separation unit. In thisembodiment, it is possible that the pure fluidic sample may betransported to the separation unit. The mobile phase serves fortransporting a packet of the fluidic sample in this other injection modewithout noteworthy mixture. Alternatively, it is possible that apredefined mixture between fluidic sample and mobile phase istransported to and separated by the separation unit. This opportunity toselect between different injection modes set by the same fluidic valvewith different characteristics in terms of sample separation furthermoreextends the flexibility of a user to adjust the injection procedure tothe requirements of a specific application, while a high degree ofcompactness of the injector may be maintained.

In the following, further embodiments of the injectors, the sampleseparation apparatus, and the methods will be explained.

It should be mentioned that the features of “a control unit configuredfor controlling a pressure of at least one of the group consisting ofthe fluid driven by the sample drive, the further fluid driven by thefluid drive, and the combined fluid during injecting fluidic sample fromthe sample accommodation volume into the flow path” and/or “a fluidiccoupling point which is defined by the fluidic valve” and/or “whereinthe fluidic valve is configured to be switchable in another injectionswitching state in which the fluidic sample is injected towards theseparation unit driven by the fluid drive while the sample accommodationvolume is located downstream of the fluid drive and upstream of theseparation unit” may be freely combined (i.e. all combinations of two orthree of these features are possible implementations of the injectors,the methods, and the sample separation apparatus according to exemplaryembodiments of the invention).

In an embodiment, the fluidic connection or flow coupler is configuredas a fluidic T-piece, a fluidic Y-piece, or a fluidic X-piece, In caseof a fluidic T-piece and a fluidic Y-piece, two flow streams arecombined at one bifurcation point into a single outlet path. In the caseof a fluidic X-piece, there may be one further fluid conduit. Thisfurther fluid conduit can be a second fluid outlet conduit or a thirdfluid inlet conduit. Other kinds of flow couplers are possible as well.

In an embodiment, the control unit is configured for controlling thepressure at or around the fluidic connection during injection.Therefore, injection can be performed reliably with a given or desiredpressure regime. This increases reproducibility of a sample separationprocedure. Additionally or alternatively, the pressure may also becontrolled, during injection, in the fluidic path connecting the sampledrive with the fluidic connection, in the fluidic path connecting thefluid drive with the fluidic connection, and/or in the fluidic pathconnecting the fluidic connection with the separation unit.

In an embodiment, the control unit is configured to keep the pressure atthe fluidic connection constant during injection. Thus, the fluid pumpedtowards and subsequently through the separation unit may be providedwith constant pressure over time. This allows for a reproducible sampleseparation. Additionally or alternatively, the pressure may also be keptconstant, during injection, in the fluidic path connecting the sampledrive with the fluidic connection, in the fluidic path connecting thefluid drive with the fluidic connection, and/or in the fluidic pathconnecting the fluidic connection with the separation unit.

In an embodiment, the control unit is configured for synchronizingoperation of the fluid drive and the sample drive for controlling thepressure. Thus, the control unit may control both the fluid drive andthe sample drive. The operation of the fluid drive and the sample drivemay hence be coordinated by a common control unit. In particular, thecontrol unit may control a first pressure with which the fluid drivepumps mobile phase. Furthermore, the control unit may control a secondpressure with which the sample drive pumps fluidic sample. Byindividually controlling a first flow rate in the flow path and a secondflow rate assigned to the sample accommodation volume, also the mixingratio of mobile phase and fluidic sample at the fluidic connection maybe precisely and flexibly adjusted.

In an embodiment, the control unit is configured for adjusting a mixingratio between mobile phase driven by the fluid drive and fluidic sampledriven by the sample drive driven towards the separation unit at thefluidic connection. This for instance allows to obtain a predefineddilution of the fluidic sample with mobile phase, if desired or requiredfor a certain application. For instance, dilution of a fluidic sample ina strong solvent (which may be desired for storage purposes) with amobile phase configured as weaker solvent may be accomplished upstreamof the separation unit and may result in a spatial concentration of theadsorption of the fluidic sample directly at an inlet of the separationunit. This increases the separation efficiency.

In an embodiment, the control unit is configured for adjusting at leastone of an outlet pressure value and an outlet flow rate value accordingto which the mixture between mobile phase and fluidic sample is driventhrough the separation unit. For example, the control unit may controlthe fluid drive and the sample drive so that a predefined or targetoutlet pressure value/target flow rate value is obtained duringoperation. For instance, the injector or the sample separation apparatusmay be controlled by the control unit in such a way, that a predefinedpressure of the mixed or combined fluid flowing into a separation unitis obtained. Alternatively, a predefined outlet flow rate (in particularan outlet volumetric flow rate, i.e. transported fluid volume per time)may be adjusted. Thus, not only the relative contribution betweenfluidic sample and mobile phase may be adjusted, but—additionally oralternatively—also the total amount per time may be adjusted inaccordance with user preferences or by automatic control. Moreover, itis possible to adjust an individual flow rate value of one of the twofluidic paths upstream of the fluidic connection, i.e. in the fluidicpath operated by the fluid drive and in the fluidic path operated by thesample drive. The described pressure and/or flow rate control allows toobtain a more flexibly operable sample separation apparatus.

More particularly, the control unit may be configured for adjustingadditionally a predefined mixing ratio between mobile phase transportedby the fluid drive and fluidic sample transported by the sample drive.For example, the control unit may control the fluid drive and the sampledrive so that the actually obtained mixing ratio equals a predefined ortarget mixing ratio. This may be accomplished by adjusting a volume overtime displacement characteristic of a respective piston of the sampledrive and/or of the fluid drive. The control unit may then drive thefluid drive and the sample drive in such a manner that the target mixingratio is obtained. This provides the user and the sample separationapparatus with a remarkably high degree of flexibility and accuracy ofthe fluid transport characteristics of the sample separation apparatus.

In an embodiment, the fluidic coupling point is located at leastpartially in an interior of the fluidic valve, in particular between astator and a rotor (compare for example FIG. 4). Hence, the fluidiccoupling point may be defined by one or more ports and one or more fluidconduits such as grooves in rotor and stator, respectively. In otherwords, a fluidic T-point or the like may be integrated into an interiorof the fluidic valve. Thus, a substantially dead volume free couplingmay be obtained. Therefore, a less complex configuration may beobtained. In fact, a fluidic T-point can be integrated into a fluidicrotor valve with low hardware effort. Providing the fluidic couplingpoint at least partially in an interior of the fluidic valve also allowsa fluidic T-piece to be configured as an only temporary fluidic T-piece,which can be established in one switching state of the fluidic valve(compare for example FIG. 4) and which may vanish upon switching thefluidic valve into another switching state (compare for example FIG. 3or FIG. 5).

In an embodiment, the fluidic valve is a rotatable fluidic valve havinga rotor and a stator being rotatable relative to one another so as tobring different fluid ports of the stator (which may optionally alsohave one or more fluid conduits) in alignment with one or morerespective fluidic conduits in the rotor. The stator may have aplurality of fluidic ports each of which being connected to a capillaryor fluidic component of the sample separation apparatus. The rotor mayhave one or a plurality of fluidic conduits such as grooves which may beselectively fluidically coupled or decoupled between respective ones ofthe fluidic ports by rotating the rotor relative to the stator.Alternatively, a longitudinally switchable fluidic valve may beimplemented.

In an embodiment, the fluidic coupling point is at least partiallydefined by one fluid port being fluidically coupled to one fluid conduitat a central position (i.e. at any position between its ends) of thisfluid conduit in the injection switching state, wherein the fluid portis further fluidically connected to a capillary guiding towards theseparation unit (compare for example reference numeral 108 in FIG. 4).In other words, the fluidic T-point may be defined by the mentionedfluidic conduit and the mentioned capillary being fluidically connectedby the mentioned fluid port. This provides a fluidic T-architecture withlow effort.

In an embodiment, the fluidic valve is an active fluidic valve beingswitchable under control of the control unit of the injector. Switchingof the fluidic valve may be triggered by the same control unit whichalso coordinates pumping of the fluid drive and/or the sample drive, toobtain a compact and properly coordinated arrangement.

In an embodiment, the injector comprises a control unit configured forcontrolling switching of the fluidic valve so as to select one of:

a feed injection mode in which the fluidic sample is injected in theinjection switching state (see FIG. 4); and

a flow-through mode in which the fluidic sample is injected in the otherinjection switching state (see FIG. 5).

In the feed injection mode, the fluidic connection between fluid driveand separation unit may be maintained while injecting the fluidic samplefrom the sample accommodation volume driven by the sample drive towardsthe separation unit. In the flow-through mode, the fluid drive may drivethe fluidic sample for injecting the fluidic sample from the sampleaccommodation volume towards the separation unit. The adjustability ofthe feed injection mode or the flow-through mode merely by switching ofa single fluidic valve into one or another switching state combines acompact configuration with a high degree of functionality andflexibility.

In an embodiment, the fluid drive and the sample drive are controllablefor injecting a predefined fluidic sample-mobile phase mixture bymixing, at the fluidic connection, the fluidic sample driven by thesample drive and a mobile phase driven by the fluid drive with apredefined mixing ratio. This allows for a defined dilution of thefluidic sample upon injection, if desired.

In an embodiment, the injector is configured for adjusting the mixingratio by adjusting a volume-over-time displacement characteristic bywhich the sample drive drives the fluidic sample. In particular, thesample drive may be configured for adjusting the volume of the fluidicsample to be injected into the flow path. Control of the pumpingcharacteristics can be accomplished by controlling the time overposition trajectory of a piston of the sample drive. For the injection,a controlled amount (such as a controlled volume or—for a temperatureindependent or pressure independent operation—a controlled amount ofmolecules) of fluidic sample can be injected at the fluidic couplingpoint. When a predefined dilution is desired, this may additionallyinvolve consideration of the flow rate (i.e. the consideration of a timefactor). When using a metering pump (such as a syringe pump), this canbe accomplished by a time-controlled displacement of a certain volume.Therefore, merely by adjusting the piston-trajectory of the sample driverelative to the operation of the fluid drive, a mixing ratio can beadjusted precisely and easily.

In an embodiment, the sample drive is operable and the fluidic valve isswitchable into a pressure adjustment switching state in which apredefined pressure (in particular overpressure for injection, inparticular overpressure above ambient pressure) is adjustable in thesample accommodation volume before switching the fluidic valve forinjecting the fluidic sample towards the separation unit.

In one alternative, pre-compressing the fluidic sample before injectingthe latter into a flow path between fluid drive and separation unit mayreduce pressure peaks upon switching. In such an alternative, thepressure in the sample accommodation volume is pre-adjusted tosubstantially correspond to the pressure in the flow path. This preventsundesired fluidic switching artefacts and increases the lifetime of thecomponents of the column. One of these artefacts is an uncontrolledvolume flow by an undefined pressure calibration at the time offluidically coupling the fluidic paths at different pressure values.

In particular, the sample drive may be operable and the fluidic valvemay be switchable so that the predefined overpressure for injectiontriggers (and in particular provides the injection force for) injectionof the fluidic sample from the sample accommodation volume towards theseparation unit by pressure equilibration, in particular without pistonmotion. Hence, in another alternative, the pressure in the sampleaccommodation volume is pre-adjusted to be larger than the pressure inthe flow path prior to the injection. In such an embodiment, the sampleaccommodation volume may be brought to a defined pressure above thepressure of the flow path. For the sake of injection at a desired pointof time, the sample accommodation volume may then be fluidicallyswitched into the flow path (which may be denoted as “overpressure forinjection” operation mode). This triggers a pressure equilibrationbetween sample accommodation volume and flow path so that, in accordancewith the present conditions, a defined volume of fluidic sample istransferred from the sample accommodation volume into the flow path.This amount is defined by the absolute pressure values, the overpressurewith regard to the flow path, the present volume of fluidic sample inthe sample accommodation volume and its compressibility. In this type ofinjection, it is not necessary that a piston of the sample drive movesat the point of time of the injection. Such a procedure can beadvantageously implemented in the event of very small injection volumes,since the definition of the injected volume by a piston trajectory ofthe sample drive might not be reducible with sufficient accuracy in sucha scenario. Another application of such an overpressure for injectionarchitecture is a sequence of multiple consecutive injections, forexample in terms of correlation chromatography.

In an embodiment, the sample drive is configured for intaking an amountof fluidic sample into the sample accommodation volume and forsubsequently injecting multiple portions of the intaken amount offluidic sample separately towards the separation unit. Thus, subsequentportions may be spaced by a respective predefined delay time. Hence, theinjector may be operated in an overfill mode. This means that a volumeof a fluidic sample accommodated in the sample accommodation volume maybe larger than an injection volume which is injected at a certain stageof the operation towards the separation unit. Therefore, it is possibleto load the sample accommodation volume once with a sufficient amount offluidic sample and to subsequently inject several portions of thefluidic sample towards the separation unit at different times orseparated by certain time intervals or delay times. Injection ofmultiple individual portions of a common filling of the sampleaccommodation volume may be adjusted by the pressure applied to thesample drive over time. Just as an example, it is possible to intake 100μl of fluidic sample and to inject ten times 10 μl of the intakenfluidic sample towards the separation unit at different times.

For instance, the described overfill mode may be advantageous when arandom run operation shall be carried out. In such a random runoperation mode, injection of multiple sample portions in accordance witha certain pattern can be carried out in order to obtain additionalinformation from a separation analysis. In this context, reference ismade to U.S. Pat. No. 3,691,364.

Another application of the described overfill mode is the study of achemical reaction. For example, a chemical reaction of the fluidicsample may be carried out in the sample accommodation volume, or on theway between the sample separation volume and the separation unit, or atthe separation unit. The kinetics of such a reaction may be tracked whenthe sample portions are analyzed by the separation unit at differentstages of the reaction. This is possible with the described overfillmode.

In an embodiment, the fluidic valve comprises a stator and a rotor beingrotatable relative to one another, wherein the stator comprises aplurality of ports and at least one fluid conduit (in particular aplurality of fluid conduits, such as one or more grooves) in permanentfluid communication with at least part of the plurality of ports, andthe rotor comprises at least one fluid conduit (in particular aplurality of fluid conduits, such as one or more grooves). The rotorconduit(s) may be selectively fluidically coupled with or decoupled fromthe stator ports and/or stator conduit(s) by rotating the rotor relativeto the stator. Such an embodiment is shown in FIG. 2 to FIG. 6B. Shortfluidic paths can be obtained by such an embodiment.

In another embodiment, the fluidic valve comprises a stator and a rotorbeing rotatable relative to one another, wherein the stator comprises aplurality of ports but no fluid conduits, and the rotor comprises atleast one fluid conduit (in particular a plurality of fluid conduits,such as one or more grooves). The rotor conduit(s) may be selectivelyfluidically coupled with or decoupled from the stator ports by rotatingthe rotor relative to the stator. Such an embodiment is shown in FIG. 7.A very simple construction of the stator can be obtained by such anembodiment.

In an embodiment, the injector comprises a needle and a seat configuredfor accommodating the needle, wherein the needle is drivable towards asample container for intaking fluidic sample into the sampleaccommodation volume by the sample drive, and wherein the needle isconfigured to be drivable to the seat prior to injection. In such aconfiguration, the fluidic sample may be stored in the sample container(such as a vial). The needle may be driven out of the seat, for instanceby a robot, and may be immersed into the fluidic sample in the samplecontainer. Subsequently, a piston of the sample drive (such as ametering pump) may be driven in a backward direction to thereby intake acertain amount of fluidic sample from the sample container via theneedle into the fluid accommodation volume. Thereafter, the needle maybe driven back into the seat to establish a fluid tight connectionthere. By switching the fluidic valve into the injection switchingstate, the intaken fluidic sample may be injected from the sampleaccommodation volume towards the separation unit.

In an embodiment, the sample drive comprises a piston configured formoving in opposite directions when intaking fluidic sample (which mayinvolve a backward motion of the piston) and when injecting fluidicsample into the flow path pressing the fluidic sample towards toseparation unit in the injection switching state. The piston may bemounted for reciprocating in a piston chamber of the sample drive. Fordrawing or intaking fluidic sample into the sample accommodation volume,the piston may be moved backwardly so as to draw fluidic sample from asample container through a needle into the sample accommodation volume.In contrast to this, for pumping fluidic sample from the sampleaccommodation volume into the flow path towards the separation unit byfeed injection, the piston may be controlled to move forwardly toprovide a sample driving force. The relation between this sample drivingforce and a mobile phase driving force by which the fluid drive drivesmobile phase towards the fluidic coupling then determines the mixingratio in the feed injection mode. Thus, sample intake and sampleinjection may involve two mutually antiparallel motion directions of thepiston.

In an embodiment, adjustment of a desired pressure value in a(decoupled) state of the sample accommodation volume prior to asubsequent coupling to another channel (such as a waste or the flowpath) may be performed for adjusting the pressure conditions in thesample accommodation volume so that no artefacts occur upon switching.Preferably, the pressure in the sample accommodation volume may bepre-adjusted to be identical to the pressure in the other channel (whichmay be denoted as pressure adjustment to avoid artefacts).

Embodiments of the above described fluidic valve may be implemented inconventionally available HPLC systems, such as the Agilent 1200 SeriesRapid Resolution LC system or the Agilent 1100 HPLC series (bothprovided by the applicant Agilent Technologies—see www.agilent.com—whichshall be incorporated herein by reference).

One embodiment of a sample separation apparatus, in which one or more ofthe above described fluidic valves may be implemented, comprises apumping apparatus as fluid drive or mobile phase drive having a pumppiston for reciprocation in a pump working chamber to compress liquid inthe pump working chamber to a high pressure at which compressibility ofthe liquid becomes noticeable. This pumping apparatus may be configuredto know (by means of operator's input, notification from another moduleof the instrument or similar) or elsewise derive solvent properties,which may be used to represent or retrieve actual properties of fluidiccontent, which is anticipated to be in a sampling apparatus.

The separation unit of the fluid separation apparatus preferablycomprises a chromatographic column (see for instanceen.wikipedia.org/wiki/Column_chromatography) providing the stationaryphase. The column may be a glass or steel tube (for instance with adiameter from 50 μm to 5 mm and a length of 1 cm to 1 m) or amicrofluidic column (as disclosed for instance in EP 1577012 or theAgilent 1200 Series HPLC-Chip/MS System provided by the applicantAgilent Technologies). The individual components are retained by thestationary phase differently and at least partly separate from eachother while they are propagating at different speeds through the columnwith the eluent. At the end of the column they elute one at a time or atleast not entirely simultaneously. During the entire chromatographyprocess the eluent may be also collected in a series of fractions. Thestationary phase or adsorbent in column chromatography usually is asolid material. The most common stationary phase for columnchromatography is silica gel, surface modified silica gel, followed byalumina. Cellulose powder has often been used in the past. Also possibleare ion exchange chromatography, reversed-phase chromatography (RP),affinity chromatography or expanded bed adsorption (EBA). The stationaryphases are usually finely ground powders or gels and/or are microporousfor an increased surface.

The mobile phase (or eluent) can be a pure solvent or a mixture ofdifferent solvents (such as water and an organic solvent such as ACN,acetonitrile). It can be chosen for instance to minimize the retentionof the compounds of interest and/or the amount of mobile phase to runthe chromatography. The mobile phase can also be chosen so that thedifferent compounds or fractions of the fluidic sample can be separatedeffectively. The mobile phase may comprise an organic solvent like forinstance methanol or acetonitrile, often diluted with water. Forgradient operation water and organic are delivered in separate bottles,from which the gradient pump delivers a programmed blend to the system.Other commonly used solvents may be isopropanol, tetrahydrofuran (THF),hexane, ethanol and/or any combination thereof or any combination ofthese with aforementioned solvents.

The fluidic sample may comprise but is not limited to any type ofprocess liquid, natural sample like juice, body fluids like plasma or itmay be the result of a reaction like from a fermentation broth.

The pressure, as generated by the fluid drive, in the mobile phase mayrange from 2-200 MPa (20 to 2000 bar), in particular 10-150 MPa (100 to1500 bar), and more particularly 50-120 MPa (500 to 1200 bar).

The sample separation apparatus, for instance an HPLC system, mayfurther comprise a detector for detecting separated compounds of thefluidic sample, a fractionating unit for outputting separated compoundsof the fluidic sample, or any combination thereof. Further details ofsuch an HPLC system are disclosed with respect to the Agilent 1200Series Rapid Resolution LC system or the Agilent 1100 HPLC series, bothprovided by the applicant Agilent Technologies, under www.agilent.comwhich shall be in cooperated herein by reference.

Embodiments of the invention can be partly or entirely embodied orsupported by one or more suitable software programs, which can be storedon or otherwise provided by any kind of data carrier, and which might beexecuted in or by any suitable data processing unit. Software programsor routines can be preferably applied in or by the control unit.

BRIEF DESCRIPTION OF DRAWINGS

Other objects and many of the attendant advantages of embodiments of thepresent invention will be readily appreciated and become betterunderstood by reference to the following more detailed description ofembodiments in connection with the accompanied drawings. Features thatare substantially or functionally equal or similar will be referred toby the same reference signs.

FIG. 1 shows a liquid sample separation apparatus in accordance withembodiments of the present invention, particularly used in highperformance liquid chromatography (HPLC).

FIG. 2 illustrates an injector according to an exemplary embodiment ofthe invention in one switching state.

FIG. 3 illustrates the injector according to an exemplary embodiment ofthe invention in another switching state.

FIG. 4 illustrates the injector according to an exemplary embodiment ofthe invention in another switching state.

FIG. 5 illustrates the injector according to an exemplary embodiment ofthe invention in another switching state.

FIG. 6A shows ports and grooves of a stator of the fluidic valveaccording to FIG. 2 to FIG. 5.

FIG. 6B shows grooves of a rotor of the fluidic valve according to FIG.2 to FIG. 5.

FIG. 7 illustrates an injector according to another exemplary embodimentof the invention having a fluidic valve with a stator having ports butno grooves and with a rotor having grooves.

The illustration in the drawing is schematic.

DETAILED DESCRIPTION

Before describing the figures in further detail, some basicconsiderations of the present invention will be summarized based onwhich exemplary embodiments have been developed.

According to an exemplary embodiment of the invention, a feed injectionarchitecture of injecting a fluidic sample towards a separation unit isprovided. In such a feed injection operation, it is possible to ejectthe fluidic sample into the main path (or flow path) without lettingflow through the metering path. Thus, by feed injection, the fluidicsample may be fed into the main path, in particular while there remainsa direct fluidic connection between a fluid drive and a mobile phasedrive on the one hand and the separation unit on the other hand. Withinthe injector configuration according to an exemplary embodiment of theinvention, the sample drive or metering device can be flushed in abypass position with an optional external pump to reduce carryover. Inan embodiment, it is also possible that the feed injection can becorrelated with pump flow. Moreover, feed injection can be donecontinuously to dilute the fluidic sample with the main pass flow, i.e.with mobile phase driven by the fluid drive. In an embodiment, it ispossible that the characteristics (in particular the speed, a dilution,etc.) of the feed injection can be adjusted dependent on method (inparticular chromatographic method) requirements. Usage of a variableloop for different injection volumes is possible according to anexemplary embodiment of the invention.

In order to design an injector and in particular a fluidic valve of aninjector according to an exemplary embodiment of the invention, it ispossible to provide only one single high pressure valve with acorresponding stator/rotor design. In an embodiment, it is possible tocalculate a compress/decompress volume. Moreover there is thepossibility to measure pressure with an additional pressure sensorin-line or differentially to determine a compress/decompress volume.

The usage of such a setup according to an exemplary embodiment providesa hydraulic injection function with the capability to compress and/ordecompress loop and/or needle and/or seat with the fluid drive ormetering device before and/or after switching into and/or out of theflow path.

Furthermore the sample drive or metering device may be purgable withfresh solvent provided by an additional flush pump. Hence, the meteringdevice may be purgable with the flush pump installed in the sampler.

With the described injector design, feed injection is possible. Thedescribed architecture is independent on solvents used in the analyticalflow path. It is possible that the sample can be introduced withmarginal influence of solvent used for the dilution of the fluidicsample. Both flow paths (i.e. needle, loop as sample accommodationvolume, seat, metering device as sample drive, versus main path,analytical pump as fluid drive, column as separation unit) can workindependently, except during the injection of fluidic sample. Therefore,the solvents used in both paths can be different.

Exemplary embodiments of the invention have several advantages. In orderto exclude the needle, seat, loop and metering device from the main pathof the analytical instrument, this setup can be used. The fluidic samplemay be injected with a plunger movement of the metering device or apre-generated overpressure (for providing an injection force forinjecting a predefined amount of fluidic sample depending on theoverpressure into the flow path) in the path of needle, seat, loop andmetering device. The injection speed may be adjustable and can be set asmethod parameter. Moreover, dilution of the fluidic sample depending onan injection mode (feed to analytical flow) and metering device plungermovement is possible in a feed mode. Both an additional flow (throughthe plunger movement of the metering device) to the main path flow and acorrelated flow, flow of plunger movement of the metering device arepossible. A compressible and decompressible path of needle, seat, loopand metering device can be implemented. In an embodiment, there are onlymarginal pressure fluctuations due to injection due to sample pathpre-compression. Multiple feed injections with one draw may be possiblein one embodiment. High frequent injections may be possible as well, forinstance for reaction monitoring. For example, a reaction can take placein the loop and can be fed partially into the mainpass just by switchingand plunger movement of the metering device. A further advantage is alow carryover due to a purge position in which also the needle can belifted to clean the needle seat interface (with solvent pumped from aflush pump). In an embodiment, the injection volume may be selectable.This is not limited, for example selectable in a range of maximum volumeof the loop installed. The described injector architecture is pressurestable over a broad range of pressures, for instance up to 1300 bar.Moreover, the described injector architecture is usable for manyapplications, for instance for supercritical fluid chromatography.

Referring now in greater detail to the drawings, FIG. 1 depicts ageneral schematic of a liquid separation system as example for a sampleseparation apparatus 10 according to an exemplary embodiment of theinvention. A pump as fluid drive 20 receives a mobile phase from asolvent supply 25, typically via a degasser 27, which degases and thusreduces the amount of dissolved gases in the mobile phase. The mobilephase drive or fluid drive 20 drives the mobile phase through aseparation unit 30 (such as a chromatographic column) comprising astationary phase. A sampler or injector 40, implementing a fluidic valve95, can be provided between the fluid drive 20 and the separation unit30 in order to subject or add (often referred to as sample introduction)a sample fluid into the mobile phase. The stationary phase of theseparation unit 30 is configured for separating compounds of the sampleliquid. A detector 50 is provided for detecting separated compounds ofthe sample fluid. A fractionating unit 60 can be provided for outputtingseparated compounds of sample fluid.

While the mobile phase can be comprised of one solvent only, it may alsobe mixed from plural solvents. Such mixing might be a low pressuremixing and provided upstream of the fluid drive 20, so that the fluiddrive 20 already receives and pumps the mixed solvents as the mobilephase. Alternatively, the fluid drive 20 might be comprised of pluralindividual pumping units, with plural of the pumping units eachreceiving and pumping a different solvent or mixture, so that the mixingof the mobile phase (as received by the separation unit 30) occurs athigh pressure and downstream of the fluid drive 20 (or as part thereof).The composition (mixture) of the mobile phase may be kept constant overtime, the so called isocratic mode, or varied over time, the so calledgradient mode.

A data processing unit or control unit 70, which can be a PC orworkstation, may be coupled (as indicated by the dotted arrows) to oneor more of the devices in the sample separation apparatus 10 in order toreceive information and/or control operation. For example, the controlunit 70 may control operation of the fluid drive 20 (e.g. settingcontrol parameters) and receive therefrom information regarding theactual working conditions (such as output pressure, etc. at an outlet ofthe fluid drive 20). The control unit 70 may also control operation ofthe solvent supply 25 (e.g. setting the solvent/s or solvent mixture tobe supplied) and/or the degasser 27 (e.g. setting control parameterssuch as vacuum level) and might receive therefrom information regardingthe actual working conditions (such as solvent composition supplied overtime, vacuum level, etc.). The control unit 70 might further controloperation of the sampling unit or injector 40 (e.g. controlling sampleinjection or synchronization of sample injection with operatingconditions of the fluid drive 20). The separation unit 30 might also becontrolled by the control unit 70 (e.g. selecting a specific flow pathor column, setting operation temperature, etc.), and send—inreturn—information (e.g. operating conditions) to the control unit 70.Accordingly, the detector 50 might be controlled by the control unit 70(e.g. with respect to spectral or wavelength settings, setting timeconstants, start/stop data acquisition), and send information (e.g.about the detected sample compounds) to the control unit 70. The controlunit 70 might also control operation of the fractionating unit 60 (e.g.in conjunction with data received from the detector 50) and provide databack.

As illustrated schematically in FIG. 1, the fluidic valve 95 can bebrought into a switching state in which a fluidic T-piece (see referencenumeral 108) is formed within the fluidic valve 95, thereby fluidicallycoupling the fluid drive 20, the separation unit 30, and a sampleaccommodation volume (compare vertical arrow in FIG. 1) of the injector40 in the shown injection switching state.

FIG. 2 to FIG. 5 illustrate an injector 40 according to an exemplaryembodiment of the invention in different switching states.

The injector 40 according to FIG. 2 to FIG. 5 is configured forinjecting a fluidic (here: liquid) sample into a flow path 104 betweenhigh pressure fluid drive 20 (configured for pumping mobile phase, i.e.a definable solvent composition) and separation unit 30, embodied as achromatographic column. For the purpose of separating the fluidic sampleinto fractions, the injector 40 comprises a sample loop or sampleaccommodation volume 100 for accommodating a certain amount of thefluidic sample prior to injecting. A sample drive 102, which can beembodied as a metering pump or syringe pump, is configured for drivingthe fluidic sample from the sample accommodation volume 100 into theflow path 104, when fluidic valve 95 is switched into a correspondingswitching state (see FIG. 4). For driving the fluidic sample towards theseparation unit 30, a piston 188 of the sample drive 102 is controlledto move forwardly. Sample drive 102 is further configured for intakingfluidic sample from a sample container (not shown) into the sampleaccommodation volume 100 by a backward motion of the piston 188. Thefluidic valve 95 can be switched in multiple switching states undercontrol of control unit 70 (see FIG. 2 to FIG. 5). By switching thefluidic valve 95, it is possible to selectively couple the sampleaccommodation volume 100 with the flow path 104 (see for instance FIG.4) or decouple the sample accommodation volume 100 from the flow path104 (see for instance FIG. 2 or FIG. 3). The control unit 70 may beconfigured for adjusting an outlet pressure value and/or an outletvolumetric flow rate value (alternatively an outlet mass flow ratevalue) according to which the mixture between mobile phase and fluidicsample is driven to the separation unit 30. In addition to theadjustment of the absolute amount of supplied fluid for time, thecontrol unit 70 may simultaneously adjust the relative mixing ratiobetween mobile phase and fluidic sample.

The fluidic valve 95 is a rotatable fluidic valve 95 having a rotor anda stator being rotatable relative to one another so as to bringdifferent fluid ports 1-6 of the stator in alignment with respectivefluidic conduits 110 in the rotor. As indicated with reference numeral155 in FIG. 2 to FIG. 5, part of the fluidic conduits 110 may beembodied as stator grooves, whereas the rest of the fluid conduits 110(not being indicated with reference numeral 155) are embodied as a rotorgrooves according to FIG. 2 to FIG. 5. This is shown in further detailin FIG. 6A, FIG. 6B. The fluidic valve 95 is an active fluidic valvebeing switchable under control of control unit 70 of the injector 40.

The injector 40 comprises a needle 112 and a seat 114 configured foraccommodating the needle 112. Although not shown in the figures, theneedle 112 is drivable towards a sample container (not shown) forintaking fluidic sample stored in the sample container into the sampleaccommodation volume 100 by the sample drive 102. The needle 112 isfurthermore configured to be drivable back to the seat 114 (as shown inFIG. 2 to FIG. 5) prior to injection.

Reference numeral 166 indicates a waste.

Referring to FIG. 2, a purge position of the fluidic valve 95 of theinjector 40 is shown. According to FIG. 2, the fluid drive 20 oranalytical pump is fluidically connected to separation unit 30 embodiedas liquid chromatography column. In the shown purge position, loop orsample accommodation volume 100, needle 112, seat 114, and sample drive102 embodied as metering device are connected to an optional flush pump180.

In the switching state according to FIG. 2, a fluidic connection isestablished from the fluid drive 20 via fluidic ports 1, 6 and conduits110, 155 of the fluidic valve 95 up to separation unit 30. A furtherfluidic connection is established from flush pump 180 via fluidic ports2, 3 and conduits 110, 155 of fluidic valve 95, sample drive 102, sampleaccommodation volume 100, needle 112, seat 114, back to fluidic valve 95and from there to waste 166.

Now referring to the switching state of FIG. 3, the sample drive 102 isoperable and the fluidic valve 95 is switched into a draw anddecompress/compress switching state in which a predefined overpressureis adjustable in the sample accommodation volume 100 before switchingthe fluidic valve 95 for injecting the fluidic sample towards theseparation unit 30.

In the draw and de-/compress position of the fluidic valve 95 accordingto FIG. 3, the fluid drive 20 or analytical pump is connected toseparation unit 30 or liquid chromatography column. Sample accommodationvolume 100 (also denoted as loop), needle 112, seat 114, and sampledrive 102 or metering device are blocked. Hence, decompressing orcompressing fluid within the injector 40 is possible in the switchingstate according to FIG. 3. Furthermore, it is possible to draw fluidicsample in the switching state according to FIG. 3.

In the switching state according to FIG. 3, a fluidic connection isestablished from the fluid drive 20 via fluidic ports 1, 6 and conduits110, 155 of the fluidic valve 95 up to separation unit 30. The flushpump 180 is disconnected. A further fluidic connection is establishedfrom sample drive 102, via sample accommodation volume 100, needle 112,seat 114, back to blocked fluidic port 5 of fluidic valve 95.

Referring to FIG. 4, the fluidic valve 95 has been switched to a feedinject position. Now, fluid drive 20 is fluidically connected to thesame flow path 104 to which also sample drive 102 is fluidicallyconnected. Sample accommodation volume 100, needle 112, seat 114, andsample drive 102 are fluidically connected to valve-internal fluidicT-piece or fluidic connection 108 which is formed by and located at theposition of static fluidic port 6 (compare FIG. 4). By defining thefluidic connection 108 or the bifurcation point of the fluidic T-pieceby static fluidic port 6 and hence as part of the stator of the fluidicvalve 95, a particular precisely defined and reproducible fluidicconnection 108 may be established with low or no dead volume. With aplunger movement of the sample drive 102 or metering device, thepreviously intaking fluidic sample can be injected towards separationunit 30.

More particularly, in an injection switching state of the fluidic valve95 as shown in FIG. 4, the fluid drive 20, the separation unit 30 andthe sample drive 102 are fluidically coupled by the fluidic valve 95 sothat fluid (such as the fluidic sample) driven by the sample drive 102and flowing from the sample accommodation volume 100 to the separationunit 30 and further fluid (such as a mobile phase, for instance asolvent composition) driven by the fluid drive 20 and flowing from thefluid drive 20 to the separation unit 30 are combined or mixed atfluidic connection 108 upstream of the separation unit 30. Thecombination of the two fluid streams at fluidic connection 108 areindicated in FIG. 4 by arrows 177, 199. Hence, both fluid streamscombine at the fluidic connection 108 to a common fluid stream flowingtowards the separation unit 30. In the injection switching stateaccording to FIG. 4, the control unit 70 is configured for controlling apressure of fluid (in particular fluidic sample) driven by the sampledrive 102 and/or further fluid (in particular a mobile phase configuredas a solvent or a solvent composition) driven by the fluid drive 20during injecting fluidic sample from the sample accommodation volume 100into the flow path 104. Consequently, in particular the pressure of thecombined fluid comprised of mobile phase and fluidic sample may becontrolled. The fluid pressure may be controlled in particular at thefluidic connection 108 between the fluid drive 20, the separation unit30 and the sample drive 102. As a basis for the operation of the system,the pressure may be measured at one or several locations (for instanceat the sample drive 102 and/or at the fluid drive 20 and/or at and/ordownstream of the fluidic connection 108, for instance by one or morepressure sensors, etc.). The measured pressure value(s) may be comparedwith a respective threshold value. Fluid drive pressure of the fluiddrive 20 and/or of the sample drive 102 may then be adjustedindividually or in common under control of control unit 70 to bring theactual pressure value(s) in accordance with the respective thresholdvalue. More specifically, the control unit 70 is configured to keep thepressure at the fluidic connection 108 constant during injection. Thecontrol unit 70 synchronizes operation of the fluid drive 20 and thesample drive 102 for controlling the pressure. In the injectionswitching state according to FIG. 4, the control unit 70 can also beconfigured for adjusting a mixing ratio between mobile phase driven bythe fluid drive 20 and fluidic sample driven by the sample drive 102towards the separation unit 30 at the fluidic connection 108. In theinjection switching state of the fluidic valve 95, the fluid drive 20,the separation unit 30 and the sample drive 102 are fluidically coupledat fluidic coupling point 108 which is defined by the fluidic valve 95.More precisely, the fluidic coupling point 108 is located in an interiorof the active fluidic valve 95 in this switching position according toFIG. 4. As can be taken from FIG. 4, the fluid drive 20 and the sampledrive 102 are controllable for injecting a predefined fluidicsample-mobile phase mixture by mixing, at the fluidic connection 108,the fluidic sample driven 102 by the sample drive 102 and a mobile phasedriven by the fluid drive 20 with a predefined mixing ratio. The mixingratio can be adjusted by adjusting the individual flow rates, inparticular by adjusting volume-over-time displacement characteristics ofthe involved pistons.

In the above described switching state according to FIG. 3, the sampledrive 102 may be also operated under control of the control unit 70 forintaking a large multi-portion amount of fluidic sample into the sampleaccommodation volume 100. Subsequently, in the switching state accordingto FIG. 4, it is possible to inject these multiple portions of thepreviously intaken amount of fluidic sample towards the separation unit30 during different discontiguous (or discontinuous) time intervals. Theindividual portions may then be separated temporally spaced by one ormore predefined delay times.

Thus, switching fluidic valve 95 of the injector 40 into the injectionswitching state according to FIG. 4, the fluidic valve 95 fluidicallycouples the fluid drive 20, the sample drive 102 and the separation unit30 at a fluidic T-point defined by the fluidic connection 108 in aninterior of the fluidic valve 95. In this injection switching state, thefluidic sample can be injected from the sample accommodation volume 100into the part of the flow path 104 guiding from the fluidic connection108 towards the separation unit 30. At the same time, another fluidstream of mobile phase is pumped from the fluid drive 20 via the fluidicconnection 108 towards the separation unit 30.

In the switching state according to FIG. 4, a fluidic connection isestablished from the fluid drive 20 via fluidic ports 1, 6 and conduits110, 155 of the fluidic valve 95 up to separation unit 30. The flushpump 180 is disconnected. A further fluidic connection is establishedfrom sample drive 102, via sample accommodation volume 100, needle 112,seat 114, back to fluidic port 5 of fluidic valve 95 and from there tofluidic connection 108. At fluidic connection 108, the fluid streamsoriginating from fluid drive 20 (via a main flow path) and originatingfrom sample drive 102 (via a metering flow path) are mixed or combined.In particular, the main flow path is between the fluid drive 20 and theseparation unit 30 (see arrow 177). The metering flow path runs from thesample drive 102, through the sample accommodation volume 100 containingthe intaken fluidic sample, the needle 112, the seat 114, and to themain flow path via the fluidic connection 108 (see arrow 199) at whichthe fluid stream in the metering flow path combines with the fluidstream of the main flow path, and after which the combined fluid streamflows to the separation unit 30 via the portion of the flow path 104downstream from the fluidic connection 108.

As can be taken from FIG. 4, the fluidic coupling point 108 in the showninjection switching mode is defined by one fluid port 6 beingfluidically coupled to one fluid conduit 110 at a central position ofthis fluid conduit 110. The fluid port 6 is further fluidicallyconnected to a capillary 111 (forming part of the flow path 104) guidingtowards the separation unit 30.

Referring to FIG. 5, an inject position is shown.

In the switching position of the fluidic valve 95 according to FIG. 5,the fluidic sample is injected towards the separation unit 30 driven bythe fluid drive 20 while the sample accommodation volume 100 is locateddownstream of the fluid drive 20 and upstream of the separation unit 30.Hence, the fluidic valve 95 does not (or no longer) form a fluidicT-piece between fluid drive 20, separation unit 30, and sampleaccommodation volume 100 in the further injection switching stateaccording to FIG. 5. In contrast to this, a continuous fluid connectionis established from fluid drive 20, via fluid valve 95, sample drive102, sample accommodation volume 100, needle 112, seat 114, againfluidic valve 95, and separation unit 30. In this other injectionswitching state, fluid driven by the fluid drive 20 flows through thesample drive 102 and the sample accommodation volume 100 before flowingto the separation unit 30.

As can be taken from a comparison of FIG. 4 and FIG. 5 differingsubstantially concerning a switching position of fluidic valve 95, thecontrol unit 70 is configured for controlling switching of the fluidicvalve 95 so as to select one of:

a feed injection mode in which the fluidic sample is injected in theinjection switching state (compare FIG. 4); or

a flow-through mode in which the fluidic sample is injected in the otherswitching state (compare FIG. 5).

In the feed injection mode of FIG. 4, a defined and adjustable mixtureor dilution of the fluidic sample with mobile phase is enabled. In theflow-through mode of FIG. 5 however, the fluidic sample is transportedas a fluid packet delimited between mobile phase packets, but beingsubstantially free of mixing or dilution. The valve design according toFIG. 2 to FIG. 5 allows to provide an injector 40 offering bothdescribed injection functionalities according to FIG. 4 or FIG. 5.

FIG. 6A shows ports 1-6 and grooves as fluid conduits 110 of a stator600 of the fluidic valve 95 according to FIG. 2 to FIG. 5. FIG. 6B showsgrooves as fluid conduits 110 of a rotor 650 of the fluidic valve 95according to FIG. 2 to FIG. 5.

FIG. 7 illustrates an injector 40 according to another exemplaryembodiment of the invention having a fluidic valve 95 with a statorhaving ports 1-6 but no grooves and with a rotor having grooves as fluidconduits 110. The embodiment of FIG. 7 differs from the embodiment ofFIG. 2 to FIG. 6B concerning shape, position and dimensioning of thegroove-type conduits 110 and concerning the position of the fluid ports1 to 6. These examples show that the functionality described referringto FIG. 2 to FIG. 6B can be achieved with different valve designs. Asindicated with reference numeral 155 in FIG. 2 to FIG. 6B, part of thefluidic conduit 110 is embodied as stator grooves, whereas the rest ofthe fluid conduits 110 (not being indicated with reference numeral 155)are embodied as a rotor grooves according to FIG. 2 to FIG. 6B. Incontrast to this, the design according to FIG. 7 does not require statorgrooves, i.e. has all fluidic conduits 110 embodied as rotor grooves.FIG. 7 furthermore shows that a fluidic restriction 171 and/or a checkvalve 144 can be implemented between the fluidic valve 95 and waste 166.This provision can also be taken according to FIG. 2 to FIG. 6B. Assubstitute for flush pump 180, the embodiment of FIG. 7 implements asolvent bottle 191.

It should be noted that the term “comprising” does not exclude otherelements or features and the term “a” or “an” does not exclude aplurality. Also elements described in association with differentembodiments may be combined. It should also be noted that referencesigns in the claims shall not be construed as limiting the scope of theclaims.

The invention claimed is:
 1. An injector for injecting a fluidic sampleinto a main flow path between a fluid drive and a separation unit of asample separation apparatus, the injector comprising: a sampleaccommodation volume configured to accommodate the fluidic sample priorto injecting; a sample drive configured to intake the fluidic sampleinto the sample accommodation volume, and to drive the intaken fluidicsample along a metering flow path from the sample accommodation volumeto the main flow path; a fluidic valve switchable between multipleswitching states to thereby selectively couple the sample accommodationvolume with the main flow path or decouple the sample accommodationvolume from the main flow path, wherein in an injection switching stateof the fluidic valve, the fluid drive, the separation unit and thesample drive are fluidically coupled by the fluidic valve so that theintaken fluidic sample, driven by the sample drive and flowing from thesample accommodation volume to the separation unit along the meteringflow path, and further fluid driven by the fluid drive and flowing fromthe fluid drive to the separation unit along the main path are combinedat a fluidic connection upstream of the separation unit; and a controlunit configured to control a pressure during injecting the fluidicsample from the sample accommodation volume into the main flow path, thepressure selected from the group consisting of: the pressure of theintaken fluidic sample driven by the sample drive; the pressure of thefurther fluid driven by the fluid drive; and the pressure of thecombined fluid as the combination of the intaken fluidic sample drivenby the sample drive and the further fluid driven by the fluid drive. 2.The injector according to claim 1, wherein the control unit isconfigured to control the pressure at the fluidic connection duringinjection.
 3. The injector according to claim 1, wherein the controlunit is configured to synchronize operation of the fluid drive and thesample drive for controlling the pressure.
 4. The injector according toclaim 1, wherein the further fluid driven by the fluid drive comprises amobile phase, and the control unit is configured to adjust a mixingratio between the mobile phase and the fluidic sample at the fluidicconnection.
 5. The injector according to claim 1, wherein the controlunit is configured to adjust at least one of a predefined total pressurevalue and a predefined outlet flow rate value according to which amixture or combination between mobile phase and fluidic sample is driventhrough the separation unit.
 6. The injector according to claim 1,wherein the fluidic valve is configured to be switchable in anotherinjection switching state in which the fluidic sample is injectedtowards the separation unit driven by the fluid drive while the sampleaccommodation volume is located downstream of the fluid drive andupstream of the separation unit.
 7. The injector according to claim 1,comprising at least one of the following features: wherein the sampledrive is configured to intake an amount of fluidic sample into thesample accommodation volume and to subsequently inject multiple portionsof the intaken amount of fluidic sample towards the separation unit,which portions are to be separated spaced by one or more predefineddelay times; wherein the fluidic valve comprises a stator and a rotorbeing rotatable relative to one another, wherein the fluidic valvecomprises one of the following features: the stator comprises aplurality of ports and at least one fluid conduit in permanent fluidcommunication with at least part of the plurality of ports, and therotor comprises at least one fluid conduit; the stator comprises aplurality of ports but no fluid conduits, and the rotor comprises atleast one fluid conduit.
 8. The injector according to claim 1, whereinthe fluid drive and the sample drive are controllable for injecting apredefined fluidic sample-mobile phase mixture by mixing, at the fluidicconnection, the fluidic sample driven by the sample drive and a mobilephase driven by the fluid drive with a predefined mixing ratio.
 9. Theinjector according to claim 8, configured to adjust the mixing ratio byadjusting a volume-over-time displacement characteristic by which thesample drive drives the fluidic sample.
 10. The injector according toclaim 1, wherein the sample drive is operable and the fluidic valve isswitchable into a pressure adjustment switching state in which apredefined overpressure for injection is adjustable in the sampleaccommodation volume before switching the fluidic valve for injectingthe fluidic sample towards the separation unit.
 11. The injectoraccording to claim 10, wherein the sample drive is operable and thefluidic valve is switchable so that the predefined overpressure forinjection triggers injection of the fluidic sample from the sampleaccommodation volume towards the separation unit by pressureequilibration, without piston motion and/or exclusively by pressureequilibration.
 12. A sample separation apparatus for separating afluidic sample, the sample separation apparatus comprising: the injectoraccording to claim 1; the fluid drive configured to drive a mobilephase; and the separation unit configured to separate the fluidic samplein the mobile phase; wherein the further fluid driven by the fluid drivecomprises the mobile phase.
 13. The sample separation apparatus of claim12, further comprising at least one of the following features: thedetector configured to detect separated fractions of the fluidic sample;the fractionating unit configured to collect separated fractions of thefluidic sample; a degassing apparatus configured to degas the mobilephase; the sample separation apparatus is configured as a chromatographysample separation apparatus.
 14. An injector for injecting a fluidicsample into a main flow path between a fluid drive and a separation unitof a sample separation apparatus, the injector comprising: a sampleaccommodation volume configured to accommodate the fluidic sample priorto injecting; a sample drive configured to intake the fluidic sampleinto the sample accommodation volume, and to drive the intaken fluidicsample along a metering flow path from the sample accommodation volumeto the main flow path; a fluidic valve switchable between multipleswitching states to thereby selectively couple the sample accommodationvolume with the main flow path or decouple the sample accommodationvolume from the main flow path, wherein in an injection switching stateof the fluidic valve, the fluid drive, the separation unit and thesample drive are fluidically coupled at a fluidic coupling point definedby a port of the fluidic valve so that the intaken fluidic sample drivenby the sample drive and flowing from the sample accommodation volume tothe separation unit and along the metering flow path, further fluiddriven by the fluid drive and flowing from the fluid drive to theseparation unit along the main flow path, are combined at the fluidiccoupling point upstream of the separation unit; and a control unitconfigured to control a pressure during injecting the fluidic samplefrom the sample accommodation volume into the main flow path, thepressure selected from the group consisting of: the pressure of theintaken fluidic sample driven by the sample drive; the pressure of thefurther fluid driven by the fluid drive; and the pressure of thecombined fluid as the combination of the intaken fluidic sample drivenby the sample drive and the further fluid driven by the fluid drive. 15.The injector according to claim 14, wherein the fluidic coupling pointis located in an interior of the fluidic valve.
 16. The injectoraccording to claim 14, wherein the fluidic valve is a rotatable fluidicvalve having a rotor and a stator being rotatable relative to oneanother so as to bring different fluid ports of the stator in alignmentwith at least one respective fluidic conduit in the rotor.
 17. Theinjector according to claim 16, wherein the fluidic coupling point is atleast partially defined by one fluid port being fluidically coupled toone fluid conduit at a central position of this fluid conduit in theinjection switching state, wherein the fluid port is further fluidicallyconnected to a capillary guiding towards the separation unit.
 18. Amethod of injecting a fluidic sample into a flow path between a fluiddrive and a separation unit of a sample separation apparatus, the methodcomprising: intaking fluidic sample in a sample accommodation volume ofan injector by a sample drive; switching a fluidic valve of the injectorinto an injection switching state in which the fluidic valve fluidicallycouples the fluid drive, the sample drive and the separation unit sothat the intaken fluidic sample driven by the sample drive and flowingfrom the sample accommodation volume to the separation unit and furtherfluid driven by the fluid drive and flowing from the fluid drive to theseparation unit are combined at a fluidic connection upstream of theseparation unit to thereby inject the fluidic sample from the sampleaccommodation volume in the flow path in the injection switching state;and controlling a pressure during the injecting, the pressure selectedfrom the group consisting of: the pressure of the intaken fluidic sampledriven by the sample drive; the pressure of the further fluid driven bythe fluid drive; and the pressure of the combined fluid as thecombination of the intaken fluidic sample driven by the sample drive andthe further fluid driven by the fluid drive.
 19. The method according toclaim 18, wherein the fluidic connection comprises a fluidic couplingpoint defined by a port of the fluidic valve.
 20. The method accordingto claim 18, comprising switching the fluidic valve in another injectionswitching state in which fluidic sample is injected towards theseparation unit driven by the fluid drive while the sample accommodationvolume is located downstream of the fluid drive and upstream of theseparation unit.